Molecular imaging is a technology in which a disease-specific image is obtained using a compound targeting a certain disease, and is applied to the diagnosis and treatment of the disease. For use in nuclear medicine imaging, radioisotopes should emit high bio-penetration radiation that can penetrate deeply into the body and be of high sensitivity. Hence, they are useable as radiotracers which guarantee good bio-images when used even in trace amounts. Representative among nuclear medicine imaging technologies are SPECT (single photon emission computed tomography) and PET (positron emission tomography). Since these technologies are configured to employ radioisotopes with a relatively short half-life, the radiotracers should be synthesized within a short period of time. Further, when a high radiation dose is used for clinical application, the overall production procedure of radiotracers, including synthesis, purification, formulation, etc., should be performed by an automatic system in a radiation-shielded space. Fabricated on the basis of a labeling reaction in liquid phase, automatic synthesizers developed so far require both very complex synthesis processes and a long period of time for the production of radiotracers, with a low synthesis yield. There is therefore a continuous need for a method for effectively synthesizing a radiopharmaceutical.